The   diagnosis   of   HPV   warts   is   usually   clinical.  A biopsy may be  helpful in establishing a diagnosis, particularly in verrucal lesions unresponsive to therapy or when warts have unusual features, such as hyperpigmentation, ulceration, rapid growth or excessive bleeding. (59) At mucosal sites, premalignant lesions (e.g. penile or vulval HSIL) caused by HPV can   be confirmed by whitening of the mucosa when acetic acid is applied. Cytologic examination is used for mucosal evaluation as well as HPV genotyping to identify high-risk subtypes. (60, 61)